Doped nitride film, doped oxide film and other doped films

ABSTRACT

Adding at least one non-silicon precursor (such as a germanium precursor, a carbon precursor, etc.) during formation of a silicon nitride, silicon oxide, silicon oxynitride or silicon carbide film improves the deposition rate and/or makes possible tuning of properties of the film, such as tuning of the stress of the film. Also, in a doped silicon oxide or doped silicon nitride or other doped structure, the presence of the dopant may be used for measuring a signal associated with the dopant, as an etch-stop or otherwise for achieving control during etching.

BACKGROUND OF INVENTION

The present invention generally relates to films used in manufacture ofsemiconductor devices, especially to nitride films and oxide films.

In order to improve drive current in complementary metal oxidesemiconductor (CMOS) devices, stressed films have been used either asspacers or middle-of-the-line (MOL) liners (also known as pre-metaldielectric (PMD) liners). Deposition regimes that result in eitherhighly tensile or highly compressive nitride films are well known (e.g.,rapid thermal chemical vapor deposition (RTCVD), plasma enhancedchemical vapor deposition (PECVD), high density plasma (HDP) usingsilicon (Si) precursor such as silane (SiH₄), di chloro silane (DCS),Disilane, Hexachlorodisilane, bis-tertiary butyl amino silane (BTBAS),and ammonia (NH₃)). However, within a given deposition regime it onlyhas been possible to modulate the stress within a small range. It hasbeen very difficult to modulate the stress to a large extent withoutcomprising the film quality.

Also, there has been a growing need for nitride/oxide films deposited ata lower temperature for MOL driven by the introduction of nitridesilicon (NiSi) processes. Many low temperature precursors have beeninvestigated, and none has turned out to be ideal.

Typically, in an LPCVD furnace, DCS and NH₃ are used for depositingsilicon nitride film at temperatures of 700 C and higher.

SUMMARY OF INVENTION

It is therefore an object of the present invention to provide increaseddeposition rate compared to conventional processes, thus providing formore manufacturable films, especially silicon nitride films, siliconoxide films, silicon oxynitride films, and silicon carbide films.

Another object of the present invention is to provide the ability toproduce good quality nitride films of varying stress levels, thusenhancing device performance as a “plug-in” solution, i.e., with nointegration changes needed.

Another object of the present invention is to lower the temperature fordeposition of a silicon nitride film, a silicon oxide film, a siliconoxynitride film or a silicon carbide film.

A further object of the present invention is to manipulate germaniumaddition during production of a silicon nitride film, silicon oxidefilm, silicon oxynitride film or silicon carbide film, to control stressin the produced film.

The present invention, in one preferred embodiment which is a process inwhich at least one Si precursor is deposited, at least one Ge precursorand/or at least one C precursor is added, to produce a Ge- and/orC-doped silicon nitride or silicon oxide film with a tunable stress.

Thus, at least one chemical or physical property (such as a stressproperty) of a silicon nitride or a silicon oxide film being producedmay be tuned by at least one precursor modification during deposition ofthe film.

Advantageously, lower-than-conventional temperature deposition can beobtained in depositing a silicon nitride, silicon oxide, siliconoxynitride or silicon carbide film according to the present invention.

The invention in one preferred embodiment provides a method of producinga doped nitride film, a doped oxide film, a doped oxynitride film or adoped carbide film, the method comprising at least: providing at leastone silicon precursor (such as, e.g., SiH₄, DCS, BTBAS, HCD, disilane,trisilane, etc.); providing at least one of: a nitrogen precursor (whichmay be the same as or different from the silicon precursor) or an oxygenprecursor; further providing at least one non-silicon precursor (whichmay be the same as or different from the silicon precursor, the nitrogenprecursor and/or the oxygen precursor); wherein a doped silicon nitridefilm, doped silicon oxide film, doped silicon oxynitride film or dopedsilicon carbide film is formed (provided that when the film is a dopedoxide, the non-silicon precursor is not boron and not phosphorous).

Examples of the non-silicon precursor for use in the inventive methodare, e.g., a germanium (Ge) precursor (such as, e.g., an organogermaniumcompound, etc.; GeH₄, GeH₃CH₃ etc.), a carbon precursor (such as, e.g.,C₂H₄, etc.); diborane; an aluminum (Al) precursor (such as, e.g.,trimethyl aluminum (TMA), AlH₃, aluminum isopropoxide etc.); a boron (B)precursor; an arsenic precursor; a hafnium precursor; a galliumprecursor (such as trimethyl Ga, trialkyl amino Ga, GaH₃, etc.); anindium precursor (such as trimethyl In, trialkyl amino In, InH₃, etc.);etc. Additionally, alkyl hydrides or alkyl amino hydrides of germanium,carbon, boron, aluminum, aluminum, arsenic, hafnium, gallium, indium,etc., may be used as precursors. In a particularly preferred example ofan inventive method, the providing of at least one silicon precursor andthe providing of at least one non-silicon precursor occurssimultaneously and is in a form of providing flow of a gas.

The inventive methods may be used for producing a variety of dopedfilms, such as, e.g., a germanium- and/or carbon-doped silicon nitrideor silicon oxide or silicon oxynitride or silicon carbide; etc.; asilicon nitride, a silicon oxide, a silicon oxynitride or a siliconcarbide film with a tunable stress; a doped silicon nitride film havinga uniformly distributed dopant concentration (such as, e.g., a Ge-dopedsilicon nitride film having a uniformly distributed Ge concentration);etc. One example of a method according to the invention is, e.g., addinggermane (a germanium precursor) to a mixture of silane and ammonia, andforming a Ge-doped Si nitride film.

In a further preferred embodiment of an inventive method, a precursormodification (such as, e.g., a mixture of at least two precursors, etc.)may be applied to tune at least one chemical or physical property of aproduced film (such as, e.g., stress of a produced film, wet etch rate;dry etch rate; etch end point; deposition rate; physical, electricaland/or optical property; etc.).

The inventive method optionally may further comprise a step of measuringa signal for a non-silicon dopant from the non-silicon precursor, saidsignal measuring for controlling an etch.

In certain embodiments of inventive methods, deposition advantageouslymay be at a lower temperature than if the non-silicon precursor wereomitted, such as, e.g., a deposition temperature below about 700° C.(including but not limited to a deposition temperature as low as roomtemperature), etc. Preferred examples of depositions in which theinventive method may be used are, e.g., RTCVD, PECVD, LPCVD, remoteplasma nitride, atomic layer deposition (ALD), etc.

The invention in other preferred embodiments provides certain films,such as, e.g., a silicon nitride, silicon oxide, silicon oxynitride orsilicon carbide film (such as, e.g., a germanium-doped film, etc.),having a tunable stress in a range of about 3 G Pa (compressive) to 3 GPa (tensile); a silicon nitride film, wherein the film is a Ge-dopedsilicon nitride film with uniformly distributed Ge; an aluminum-dopedsilicon oxide film; a germanium-doped silicon nitride film; etc.; aGe-doped film wherein the Ge-doped film has a stress that is at leastabout 1.0 G Pa greater (preferably, 1.2 G Pa greater) than a film thathas been made by a same process except without Ge-doping.

Inventive films may include one or more dopants, such as a multitude ofdopants. Examples of dopants for use in inventive films include, e.g.,germanium (Ge), carbon (C), boron (B), aluminum (Al), gallium (Ga),indium (In), etc., which dopants may be used singly or in combination.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other objects, aspects and advantages will be betterunderstood from the following detailed description of a preferredembodiment of the invention with reference to the drawings, in which:

FIG. 1 is a chart of ellipsometry measurements (49 points) for onesilicon nitride film and two LPCVD SiGe Nitride films.

FIG. 2 is a chart of etch rate of one silicon nitride film and two SiGenitride films, based on ellipsometry, 49 points, with FIG. 2 relating tothe films charted in FIG. 1.

FIG. 3 is a chart of deposition rate as function of Ge incorporation,with plots for with and without Ge, with FIG. 3 relating to the filmscharted in FIG. 1.

FIG. 4 is a side view showing a stressed liner according to anembodiment of the invention, with the stressed liner in use with aspacer, a gate and a channel.

FIGS. 5A-5C depict an endpoint detection method according to anembodiment of the invention.

DETAILED DESCRIPTION

In the present invention, during production of a doped nitride film, adoped oxide film, a doped oxynitride film or a doped carbide film, atleast one of the following is manipulated: the deposition rate; achemical and/or physical property (such as, e.g., tunable stress) of theformed film. This manipulation is accomplished by introducing anadditional non-silicon precursor that is otherwise not a traditionalreagent for producing a nitride film, an oxide film, an oxynitride film,or a carbide film, with examples of the additional non-silicon precursorbeing a germanium precursor and a carbon precursor.

The present invention accomplishes such advantages by including anon-silicon precursor dopant (such as, e.g., a Ge precursor, etc.)during the deposition process, such as deposition of a silicon nitridefilm, deposition of a silicon oxide film, deposition of a siliconoxynitride film, deposition of a silicon carbide film, etc.

For example, in one embodiment, the present invention makes possiblelow-temperature deposition of a nitride film, an oxide film, anoxynitride film and/or a carbide film, by adding germanium to depositionof nitride films and oxide films and oxynitride films and carbide films,especially doped nitride or oxide films. The present inventors exploitthe fact that silicon germanium (SiGe) epitaxy can be done at a lowertemperature than silicon epitaxy, and further have discovered that theaddition of a germanium (Ge) precursor to a silicon precursor lowers thetemperature of the deposition of the film.

A germanium precursor used in the present invention may be, e.g., aknown germanium precursor such as the germanium precursors mentioned,e.g., in U.S. Pat. No. 6,429,098 issued Aug. 6, 2002 and U.S. Pat. No.6,117,750 issued Sep. 12, 2000 to Bensahel et al. (France Telecom) or inU.S. Pat. No. 6,258,664 issued Jul. 10, 2001 to Reinberg (MicronTechnology, Inc.). Germanium precursors are commercially available. Anexample of a germanium precursor used in the invention is GeH₄.

The present invention provides for use of at least one germaniumprecursor in deposition of a silicon nitride, a silicon oxide, a siliconoxynitride, a silicon carbide, etc., which deposition advantageouslymay, if desired, by a low-temperature deposition, such as, e.g., adeposition at 700° C. or lower, such as, e.g., room temperature andother temperatures. In a preferred example, an inventive method mayproceed at room temperature in a P3i plasma immersion tool, to depositnitride.

When including the non-silicon precursor in the present invention forproducing a silicon nitride or silicon oxide film or silicon oxynitridefilm or silicon carbide film, the production process otherwise mayproceed conventionally with regard to ingredients, for example, use of anitrogen precursor (such as, e.g., NH₃, etc.) and a silicon precursor(such as DCS, etc.), etc. For producing a silicon nitride film, anitrogen precursor is included. For producing a silicon oxide film, anoxygen precursor is included. For producing a silicon nitride or asilicon oxide film, a silicon precursor is included. It will beappreciated that the silicon precursor may be different or the same asthe nitride or oxide precursor. For example, BTBAS may serve as asilicon precursor and a nitrogen precursor. In the present invention, insome embodiments a reagent (such as, e.g., BTBAS, etc.) optionally maybe used as two or more kinds of precursors.

An exemplary temperature for nitride or oxide or oxynitride or carbidefilm forming using a germanium precursor and/or a carbon precursoraccording to the invention is preferably at a temperature less than 700°C., more preferably at a temperature less than 650° C., even morepreferably at a temperature of 500° C. or lower. For example, in thecase of Ge-doping, an advantageous temperature of 500° C. or lower maybe used for the deposition of a Ge-doped silicon nitride film. It willbe appreciated that, while the present invention advantageously makespossible relatively low deposition temperatures that are desirable, lowdeposition temperatures are not necessarily required to be used in allembodiments, such as, for example, a film may be advantageouslystress-tuned according to the invention at a variety of depositiontemperatures.

The non-silicon precursor mentioned for use in the present invention isnot particularly limited, and as examples may be mentioned a germaniumprecursor, a carbon precursor, an aluminum precursor, a boron precursor,an arsenic precursor, a hafnium precursor, a gallium precursor, anindium precursor, and, without limitation, other dopant precursors, etc.

The present invention also may be applied to MOL barrier technology. Forexample, it is well known that the MOL barrier nitride can enhancedevice reliability (negative bias temperature instability (NBTI), etc.).The present invention provides, through use of the germanium precursorand/or the carbon precursor, an ability to tune the chemical and/orphysical properties of the barrier nitride film using differentprecursor combinations. Such an ability may be used to achieve asignificant device reliability gain.

Thickness of a film produced according to the present invention is notparticularly limited, and a thickness may be selected depending on theapplication. The film thickness may range from, on the thin end (suchas, e.g., a film of 500 Angstroms, or of 10 Angstroms, or thinner), tothe thick end (such as, e.g., a film of 1,000 Angstroms, or a film of5,000 Angstroms, or thicker), and thicknesses in between, such as filmsin a range of about 10 to 5,000 Angstroms, and thinner or thicker ascalled for by the application.

The dopant concentration of a film made according to the invention isnot particularly, and may be adjusted as desired. An example of a dopant(such as Ge, etc.) concentration is in a range of, e.g., about 1 to 10%,or, in another example, about 1 to 50%.

The present invention includes an embodiment in which multiplenon-silicon precursors are used, such as a germanium precursor and acarbon precursor; a germanium precursor and a boron precursor; etc. Forexample, adding multiple precursors during deposition of a siliconnitride or a silicon oxide film may provide an enhanced effect, as maybe desired.

The present invention may be used, e.g., for signaling an etch endpoint. For example, when conventional silicon nitride etching isperformed, there has been a problem with wanting to stop the etch at theend of the silicon nitride and not etch over onto the silicon. However,such an etch end point many times has not been sharp and etching intothe silicon has been common with the conventional methods. With thepresent invention, if a doped silicon nitride is used (such as aGe-doped silicon nitride), the presence of the Ge in the silicon nitridemay be used to signal the endpoint of the etch, thereby advantageouslypreventing over-etching, such as, e.g., by using optical emissionspectroscopy to detect the Ge (e.g., a Ge-Fluoride signal may besearched-for).

Such an aforementioned etch-stop example is not limiting, and theinvention is extended to a variety of signaling uses of a dopant in adoped nitride film or a doped oxide film. For example, there may beprovided a thin silicon nitride layer doped as an etch stop layer (suchas a Ge-doped silicon nitride layer, etc.), and the dopant signal (e.g.,the Ge signal, etc.) may be monitored for determining where the layerbegins. A number of different implementations of the present inventionmay be provided, in the etching context. Another example is a thin layerof carbon or boron doped oxide under a Ge-doped nitride. For such astructure, drop in Ge signal and advent of C signal can be monitored,for better etching results. A further example of using the invention inan etching process is use of two different dopants, such as providingone dopant in each of the respective layers, or providing the twodifferent dopants in a same layer. It will be appreciated that thepresent invention includes use of different signals being controlled formaximal sensitivity, and that the above-mentioned are only someexamples.

Another use of the present invention is to change stress of a producedfilm (e.g., a silicon nitride, silicon oxide) by including a dopant,compared to a film in which the dopant is not included. For example, fora case of a silicon nitride film, inclusion of a Ge dopant has beenfound to change stress of the film to the tensile region.Conventionally, RTCVD silicon nitride films have a stress of about 1 to1.5 G Pa (tensile). Including Ge in the silicon nitride films provides asignificant change raising the stress of the film, such as a dopedGe-silicon nitride film with a stress exceeding 1.5 G Pa (tensile), suchas a stress of 2 G Pa (tensile), or higher, etc. When measuring a filmdoped according to the invention and a comparable non-doped film on thesame stress tool, a delta of 1 G Pa or greater (preferably, such as adelta of 1.2 G Pa or greater) may be obtained in the doped film. Also,the present invention may be used to change the stress of a film fromcompressive to tensile, which signifies a significant change in thenature of a film.

Thus, the present invention advantageously may be used to tune stress ofa silicon nitride or silicon oxide film or silicon oxynitride or siliconcarbide film as desired.

Also, the present invention may be used to produce doped silicon nitridefilms, doped silicon oxide films, doped silicon oxynitride films, anddoped silicon carbide films, such as, e.g., a Ge-doped silicon nitridefilm, an Al-doped silicon oxide film, a boron-doped silicon nitridefilm, etc.

EXAMPLE 1

In an LPCVD furnace, GEH₄ was added to a mixture of DCS and NH₃ at twodifferent temperatures, 700 and 650° C. respectively. A standard siliconnitride film was also deposited at 785° C. as a control. Twogermanium-doped silicon nitride films and one standard silicon nitridefilm were thus deposited. The results are summarized in the charts whichare FIGS. 1, 2 and 3.

In FIG. 1, the top plot is for the film deposited at 785° C., withDCS/NH₂=0.3 The middle plot in FIG. 1 is for the film deposited at 700°C., with (DCS+Ge)/NH₃=0.3, Ge/DCS=0.25. The bottom plot in FIG. 1 is forthe film deposited at 650° C., with the same ratios as for the filmdeposited at 700° C.

From FIG. 3, it is clear that by adding GeH₄ to the process gas, asignificant increase in the deposition rate has been achieved. Also, thegermanium-doped films of this Example 1 have a similar property(determined by wet etch rate) to the standard high temperature films.

The addition of germane to a mixture of a silicon precursor and ammoniaallows for: Increasing the deposition rate of an existing process makingthe process more manufacturable; lowering the deposition rate of aprocess to make it extendable to future technology; and/or manipulatingstress of the formed film.

EXAMPLE 2

Importantly, the present Inventors have recognized that stress in a filmmay be modified by germanium addition during nitride film formation.There may be considered the following results, both for siliconsubstrates: (i) for a Si—N film, stress of 4 E9 Dyne/cm² (compressive);(ii) for a SiGe—N film, stress of 8.2 E9 Dyne/cm (tensile).

As the above data shows, there is almost an order of magnitude stressdifference between a conventional silicon nitride film and an inventivegermanium-doped silicon nitride film.

It will be appreciated that the advantages of the present invention withregard to deposition rate and/or stress tuning are not limited tonitride films, and may be applicable for oxide films (such as siliconoxide films, etc.) and other films, such as other amorphous films.

EXAMPLE 3

Ge was added to a mixture of silane and ammonia, forming a Ge-doped Sinitride film. The deposition rate was increased for the germane process,compared to an equivalent no-germane process. For the no-Ge processs,the stress of the produced film was 0.4 GPa (compressive). For theinventive process using Ge, the stress was 0.8 GPa (tensile). Thus, theuse of Ge according to the invention achieved a change in stress of 1.2GPa, which was a substantial improvement.

EXAMPLE 4

With reference to FIG. 4, an example of a stressed film according to oneembodiment of the invention is shown. Stressed nitride liner 40(produced according to the invention) is shown in use with spacer 41,gate (POLY) with layer 44 (silicide), with the gate being over a channel(SOI).

EXAMPLE 5

With reference to FIGS. 5A-5C, an example of a counter-doped nitride oroxide layer for endpoint detection according to the invention is shown.Referring to FIG. 5A, in a device including gate 52, a spacer nitride 51(with a first dopant) is provided over a nitride or oxide layer 50 (witha second dopant). The as-deposited films of FIG. 5A are processedaccording to an initial RIE step shown in FIG. 5B, wherein duringinitial RIE, the first dopant is detected. Next, a step of final RIE isperformed, as shown in FIG. 5C, wherein an etch endpoint is reached.During the final RIE step, a smaller amount of the first dopant (in thespacer nitride 51 or etched spacer nitride 51′) is detected, anddetection of the second dopant (in the nitride or oxide layer 50)begins. After the etch endpoint step, a controllably etched spacernitride 51′ remains.

While the invention has been described in terms of its preferredembodiment, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theappended claims.

1. A method of producing a doped silicon nitride film, doped siliconoxide film, doped silicon oxynitride film or doped silicon carbide film,the method comprising at least: providing at least one siliconprecursor, providing at least one of: a nitrogen precursor (which may bethe same as or different from the silicon precursor) or an oxygenprecursor, further providing at least one non-silicon precursor (whichmay be the same as or different from the silicon precursor, the nitrogenprecursor and/or the oxygen precursor), wherein a doped silicon nitridefilm, a doped silicon oxide film, a doped silicon oxynitride film or adoped silicon carbide film is formed (provided that when the film is adoped oxide, the non-silicon precursor is not boron and notphosphorous).
 2. The method of claim 1, wherein the providing of atleast one silicon precursor and the providing of at least onenon-silicon precursor occurs simultaneously and is in a form ofproviding flow of a gas.
 3. The method of claim 1, wherein thenon-silicon precursor is a germanium precursor.
 4. The method of claim1, wherein the non-silicon precursor is selected from the groupconsisting of a carbon precursor; a boron precursor; an aluminumprecursor; an arsenic precursor; a hafnium precursor; a galliumprecursor and an indium precursor.
 5. The method of claim 1, wherein aproduced film is a silicon nitride film.
 6. The method of claim 1,wherein a produced film is germanium- and/or carbon-doped siliconnitride or silicon oxide.
 7. The method of claim 1, wherein a producedfilm has a tunable stress.
 8. The method of claim 1, wherein thenon-silicon precursor is an organogermanium compound or a germaniumprecursor selected from the group consisting of GeH₄ and GeH₃CH₃;diborane; trimethyl aluminum (TMA); a C₂H₄ carbon precursor; trimethylGa; trimethyl In; trialkyl amino Ga; trialkyl amino In; GaH₃; InH₃; AlH₃or aluminum isopropoxide.
 9. The method of claim 1, wherein thenon-silicon precursor is an alkyl hydride or an alkyl amino hydride ofgermanium, carbon, aluminum, boron, arsenic, hafnium, gallium or indium.10. The method of claim 1, including applying a precursor modificationto tune at least one chemical or physical property of a produced film.11. The method of claim 10, wherein the precursor modification is amixture of at least two precursors.
 12. The method of claim 10, whereinthe at least one chemical or physical property is stress of a producedfilm.
 13. The method of claim 10, wherein the at least one chemical orphysical property is selected from the group consisting of: wet etchrate; dry etch rate; etch end point; deposition rate; and physical,electrical and/or optical property.
 14. The method of claim 1, whereindeposition is at a lower temperature than if the non-silicon precursorwere omitted.
 15. The method of claim 1, conducted at a temperaturebelow about 700° C.
 16. The method of claim 1, wherein the deposition isRTCVD, PECVD, LPCVD, remote plasma nitride or ALD.
 17. The method ofclaim 1, including adding germane to a mixture of silane and ammonia,and forming a Ge-doped Si nitride film.
 18. The method of claim 1,further comprising a step of measuring a signal for a non-silicon dopantfrom the non-silicon precursor, said signal measuring for controlling anetch.
 19. The method of claim 1, wherein the produced film is a Ge-dopedsilicon nitride film having a uniformly distributed Ge concentration.20-27. (canceled)
 28. The method of claim 1, wherein the deposition isconducted at room temperature.